The question of Licenses and Terms of Use is especially important for an Open-Source CMS, but even commercial system licenses need to be understood carefully. The allowed use may be only for a single CPU, and to realize full scalability may involve additional licenses even for a single CMS installation.

Here are several interesting questions about licences.

Are software licenses revokable (even if stated as perpetual)?
See this Advogato article

Note that, for public policy reasons, under the Copyright Act all
licenses are terminable "at any time during a period of five years
beginning at the end of thirty-five years from the date of execution of
the grant...." 17 U.S.C. 203(a)(3). This is true even if the license
states that it is "perpetual." Even in that rare situation, though,
derivative works prepared before termination may continue to be used but
no additional derivative works may be created.